/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/

/*
 *  HMAC_DRBG implementation (NIST SP 800-90)
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

/*
 *  The NIST SP 800-90A DRBGs are described in the following publication.
 *  http://csrc.nist.gov/publications/nistpubs/800-90A/SP800-90A.pdf
 *  References below are based on rev. 1 (January 2012).
 */

#include "tls/config.h"

#if defined(MBEDTLS_HMAC_DRBG_C)

#include "tls/hmac_drbg.h"

#include <string.h>

#if defined(MBEDTLS_FS_IO)
#include <stdio.h>
#endif

#if defined(MBEDTLS_SELF_TEST)
#if defined(MBEDTLS_PLATFORM_C)
#include "tls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf printf
#endif							/* MBEDTLS_SELF_TEST */
#endif							/* MBEDTLS_PLATFORM_C */

/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize(void *v, size_t n)
{
	volatile unsigned char *p = v;
	while (n--) {
		*p++ = 0;
	}
}

/*
 * HMAC_DRBG context initialization
 */
void mbedtls_hmac_drbg_init(mbedtls_hmac_drbg_context *ctx)
{
	memset(ctx, 0, sizeof(mbedtls_hmac_drbg_context));

#if defined(MBEDTLS_THREADING_C)
	mbedtls_mutex_init(&ctx->mutex);
#endif
}

/*
 * HMAC_DRBG update, using optional additional data (10.1.2.2)
 */
void mbedtls_hmac_drbg_update(mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t add_len)
{
	size_t md_len = mbedtls_md_get_size(ctx->md_ctx.md_info);
	unsigned char rounds = (additional != NULL && add_len != 0) ? 2 : 1;
	unsigned char sep[1];
	unsigned char K[MBEDTLS_MD_MAX_SIZE];

	for (sep[0] = 0; sep[0] < rounds; sep[0]++) {
		/* Step 1 or 4 */
		mbedtls_md_hmac_reset(&ctx->md_ctx);
		mbedtls_md_hmac_update(&ctx->md_ctx, ctx->V, md_len);
		mbedtls_md_hmac_update(&ctx->md_ctx, sep, 1);
		if (rounds == 2) {
			mbedtls_md_hmac_update(&ctx->md_ctx, additional, add_len);
		}
		mbedtls_md_hmac_finish(&ctx->md_ctx, K);

		/* Step 2 or 5 */
		mbedtls_md_hmac_starts(&ctx->md_ctx, K, md_len);
		mbedtls_md_hmac_update(&ctx->md_ctx, ctx->V, md_len);
		mbedtls_md_hmac_finish(&ctx->md_ctx, ctx->V);
	}
}

/*
 * Simplified HMAC_DRBG initialisation (for use with deterministic ECDSA)
 */
int mbedtls_hmac_drbg_seed_buf(mbedtls_hmac_drbg_context *ctx, const mbedtls_md_info_t *md_info, const unsigned char *data, size_t data_len)
{
	int ret;

	if ((ret = mbedtls_md_setup(&ctx->md_ctx, md_info, 1)) != 0) {
		return (ret);
	}

	/*
	 * Set initial working state.
	 * Use the V memory location, which is currently all 0, to initialize the
	 * MD context with an all-zero key. Then set V to its initial value.
	 */
	mbedtls_md_hmac_starts(&ctx->md_ctx, ctx->V, mbedtls_md_get_size(md_info));
	memset(ctx->V, 0x01, mbedtls_md_get_size(md_info));

	mbedtls_hmac_drbg_update(ctx, data, data_len);

	return (0);
}

/*
 * HMAC_DRBG reseeding: 10.1.2.4 (arabic) + 9.2 (Roman)
 */
int mbedtls_hmac_drbg_reseed(mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t len)
{
	unsigned char seed[MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT];
	size_t seedlen;

	/* III. Check input length */
	if (len > MBEDTLS_HMAC_DRBG_MAX_INPUT || ctx->entropy_len + len > MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT) {
		return (MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG);
	}

	memset(seed, 0, MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT);

	/* IV. Gather entropy_len bytes of entropy for the seed */
	if (ctx->f_entropy(ctx->p_entropy, seed, ctx->entropy_len) != 0) {
		return (MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED);
	}

	seedlen = ctx->entropy_len;

	/* 1. Concatenate entropy and additional data if any */
	if (additional != NULL && len != 0) {
		memcpy(seed + seedlen, additional, len);
		seedlen += len;
	}

	/* 2. Update state */
	mbedtls_hmac_drbg_update(ctx, seed, seedlen);

	/* 3. Reset reseed_counter */
	ctx->reseed_counter = 1;

	/* 4. Done */
	return (0);
}

/*
 * HMAC_DRBG initialisation (10.1.2.3 + 9.1)
 */
int mbedtls_hmac_drbg_seed(mbedtls_hmac_drbg_context *ctx, const mbedtls_md_info_t *md_info, int (*f_entropy)(void *, unsigned char *, size_t), void *p_entropy, const unsigned char *custom, size_t len)
{
	int ret;
	size_t entropy_len, md_size;

	if ((ret = mbedtls_md_setup(&ctx->md_ctx, md_info, 1)) != 0) {
		return (ret);
	}

	md_size = mbedtls_md_get_size(md_info);

	/*
	 * Set initial working state.
	 * Use the V memory location, which is currently all 0, to initialize the
	 * MD context with an all-zero key. Then set V to its initial value.
	 */
	mbedtls_md_hmac_starts(&ctx->md_ctx, ctx->V, md_size);
	memset(ctx->V, 0x01, md_size);

	ctx->f_entropy = f_entropy;
	ctx->p_entropy = p_entropy;

	ctx->reseed_interval = MBEDTLS_HMAC_DRBG_RESEED_INTERVAL;

	/*
	 * See SP800-57 5.6.1 (p. 65-66) for the security strength provided by
	 * each hash function, then according to SP800-90A rev1 10.1 table 2,
	 * min_entropy_len (in bits) is security_strength.
	 *
	 * (This also matches the sizes used in the NIST test vectors.)
	 */
	entropy_len = md_size <= 20 ? 16 :	/* 160-bits hash -> 128 bits */
				  md_size <= 28 ? 24 :	/* 224-bits hash -> 192 bits */
				  32;						/* better (256+) -> 256 bits */

	/*
	 * For initialisation, use more entropy to emulate a nonce
	 * (Again, matches test vectors.)
	 */
	ctx->entropy_len = entropy_len * 3 / 2;

	if ((ret = mbedtls_hmac_drbg_reseed(ctx, custom, len)) != 0) {
		return (ret);
	}

	ctx->entropy_len = entropy_len;

	return (0);
}

/*
 * Set prediction resistance
 */
void mbedtls_hmac_drbg_set_prediction_resistance(mbedtls_hmac_drbg_context *ctx, int resistance)
{
	ctx->prediction_resistance = resistance;
}

/*
 * Set entropy length grabbed for reseeds
 */
void mbedtls_hmac_drbg_set_entropy_len(mbedtls_hmac_drbg_context *ctx, size_t len)
{
	ctx->entropy_len = len;
}

/*
 * Set reseed interval
 */
void mbedtls_hmac_drbg_set_reseed_interval(mbedtls_hmac_drbg_context *ctx, int interval)
{
	ctx->reseed_interval = interval;
}

/*
 * HMAC_DRBG random function with optional additional data:
 * 10.1.2.5 (arabic) + 9.3 (Roman)
 */
int mbedtls_hmac_drbg_random_with_add(void *p_rng, unsigned char *output, size_t out_len, const unsigned char *additional, size_t add_len)
{
	int ret;
	mbedtls_hmac_drbg_context *ctx = (mbedtls_hmac_drbg_context *)p_rng;
	size_t md_len = mbedtls_md_get_size(ctx->md_ctx.md_info);
	size_t left = out_len;
	unsigned char *out = output;

	/* II. Check request length */
	if (out_len > MBEDTLS_HMAC_DRBG_MAX_REQUEST) {
		return (MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG);
	}

	/* III. Check input length */
	if (add_len > MBEDTLS_HMAC_DRBG_MAX_INPUT) {
		return (MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG);
	}

	/* 1. (aka VII and IX) Check reseed counter and PR */
	if (ctx->f_entropy != NULL &&	/* For no-reseeding instances */
		(ctx->prediction_resistance == MBEDTLS_HMAC_DRBG_PR_ON || ctx->reseed_counter > ctx->reseed_interval)) {
		if ((ret = mbedtls_hmac_drbg_reseed(ctx, additional, add_len)) != 0) {
			return (ret);
		}

		add_len = 0;			/* VII.4 */
	}

	/* 2. Use additional data if any */
	if (additional != NULL && add_len != 0) {
		mbedtls_hmac_drbg_update(ctx, additional, add_len);
	}

	/* 3, 4, 5. Generate bytes */
	while (left != 0) {
		size_t use_len = left > md_len ? md_len : left;

		mbedtls_md_hmac_reset(&ctx->md_ctx);
		mbedtls_md_hmac_update(&ctx->md_ctx, ctx->V, md_len);
		mbedtls_md_hmac_finish(&ctx->md_ctx, ctx->V);

		memcpy(out, ctx->V, use_len);
		out += use_len;
		left -= use_len;
	}

	/* 6. Update */
	mbedtls_hmac_drbg_update(ctx, additional, add_len);

	/* 7. Update reseed counter */
	ctx->reseed_counter++;

	/* 8. Done */
	return (0);
}

/*
 * HMAC_DRBG random function
 */
int mbedtls_hmac_drbg_random(void *p_rng, unsigned char *output, size_t out_len)
{
	int ret;
	mbedtls_hmac_drbg_context *ctx = (mbedtls_hmac_drbg_context *)p_rng;

#if defined(MBEDTLS_THREADING_C)
	if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
		return (ret);
	}
#endif

	ret = mbedtls_hmac_drbg_random_with_add(ctx, output, out_len, NULL, 0);

#if defined(MBEDTLS_THREADING_C)
	if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
		return (MBEDTLS_ERR_THREADING_MUTEX_ERROR);
	}
#endif

	return (ret);
}

/*
 * Free an HMAC_DRBG context
 */
void mbedtls_hmac_drbg_free(mbedtls_hmac_drbg_context *ctx)
{
	if (ctx == NULL) {
		return;
	}
#if defined(MBEDTLS_THREADING_C)
	mbedtls_mutex_free(&ctx->mutex);
#endif
	mbedtls_md_free(&ctx->md_ctx);
	mbedtls_zeroize(ctx, sizeof(mbedtls_hmac_drbg_context));
}

#if defined(MBEDTLS_FS_IO)
int mbedtls_hmac_drbg_write_seed_file(mbedtls_hmac_drbg_context *ctx, const char *path)
{
	int ret;
	FILE *f;
	unsigned char buf[MBEDTLS_HMAC_DRBG_MAX_INPUT];

	if ((f = fopen(path, "wb")) == NULL) {
		return (MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR);
	}

	if ((ret = mbedtls_hmac_drbg_random(ctx, buf, sizeof(buf))) != 0) {
		goto exit;
	}

	if (fwrite(buf, 1, sizeof(buf), f) != sizeof(buf)) {
		ret = MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR;
		goto exit;
	}

	ret = 0;

exit:
	fclose(f);
	return (ret);
}

int mbedtls_hmac_drbg_update_seed_file(mbedtls_hmac_drbg_context *ctx, const char *path)
{
	FILE *f;
	size_t n;
	unsigned char buf[MBEDTLS_HMAC_DRBG_MAX_INPUT];

	if ((f = fopen(path, "rb")) == NULL) {
		return (MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR);
	}

	fseek(f, 0, SEEK_END);
	n = (size_t)ftell(f);
	fseek(f, 0, SEEK_SET);

	if (n > MBEDTLS_HMAC_DRBG_MAX_INPUT) {
		fclose(f);
		return (MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG);
	}

	if (fread(buf, 1, n, f) != n) {
		fclose(f);
		return (MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR);
	}

	fclose(f);

	mbedtls_hmac_drbg_update(ctx, buf, n);

	return (mbedtls_hmac_drbg_write_seed_file(ctx, path));
}
#endif							/* MBEDTLS_FS_IO */

#if defined(MBEDTLS_SELF_TEST)

#if !defined(MBEDTLS_SHA1_C)
/* Dummy checkup routine */
int mbedtls_hmac_drbg_self_test(int verbose)
{
	(void)verbose;
	return (0);
}
#else

#define OUTPUT_LEN  80

/* From a NIST PR=true test vector */
static const unsigned char entropy_pr[] = {
	0xa0, 0xc9, 0xab, 0x58, 0xf1, 0xe2, 0xe5, 0xa4, 0xde, 0x3e, 0xbd, 0x4f,
	0xf7, 0x3e, 0x9c, 0x5b, 0x64, 0xef, 0xd8, 0xca, 0x02, 0x8c, 0xf8, 0x11,
	0x48, 0xa5, 0x84, 0xfe, 0x69, 0xab, 0x5a, 0xee, 0x42, 0xaa, 0x4d, 0x42,
	0x17, 0x60, 0x99, 0xd4, 0x5e, 0x13, 0x97, 0xdc, 0x40, 0x4d, 0x86, 0xa3,
	0x7b, 0xf5, 0x59, 0x54, 0x75, 0x69, 0x51, 0xe4
};

static const unsigned char result_pr[OUTPUT_LEN] = {
	0x9a, 0x00, 0xa2, 0xd0, 0x0e, 0xd5, 0x9b, 0xfe, 0x31, 0xec, 0xb1, 0x39,
	0x9b, 0x60, 0x81, 0x48, 0xd1, 0x96, 0x9d, 0x25, 0x0d, 0x3c, 0x1e, 0x94,
	0x10, 0x10, 0x98, 0x12, 0x93, 0x25, 0xca, 0xb8, 0xfc, 0xcc, 0x2d, 0x54,
	0x73, 0x19, 0x70, 0xc0, 0x10, 0x7a, 0xa4, 0x89, 0x25, 0x19, 0x95, 0x5e,
	0x4b, 0xc6, 0x00, 0x1d, 0x7f, 0x4e, 0x6a, 0x2b, 0xf8, 0xa3, 0x01, 0xab,
	0x46, 0x05, 0x5c, 0x09, 0xa6, 0x71, 0x88, 0xf1, 0xa7, 0x40, 0xee, 0xf3,
	0xe1, 0x5c, 0x02, 0x9b, 0x44, 0xaf, 0x03, 0x44
};

/* From a NIST PR=false test vector */
static const unsigned char entropy_nopr[] = {
	0x79, 0x34, 0x9b, 0xbf, 0x7c, 0xdd, 0xa5, 0x79, 0x95, 0x57, 0x86, 0x66,
	0x21, 0xc9, 0x13, 0x83, 0x11, 0x46, 0x73, 0x3a, 0xbf, 0x8c, 0x35, 0xc8,
	0xc7, 0x21, 0x5b, 0x5b, 0x96, 0xc4, 0x8e, 0x9b, 0x33, 0x8c, 0x74, 0xe3,
	0xe9, 0x9d, 0xfe, 0xdf
};

static const unsigned char result_nopr[OUTPUT_LEN] = {
	0xc6, 0xa1, 0x6a, 0xb8, 0xd4, 0x20, 0x70, 0x6f, 0x0f, 0x34, 0xab, 0x7f,
	0xec, 0x5a, 0xdc, 0xa9, 0xd8, 0xca, 0x3a, 0x13, 0x3e, 0x15, 0x9c, 0xa6,
	0xac, 0x43, 0xc6, 0xf8, 0xa2, 0xbe, 0x22, 0x83, 0x4a, 0x4c, 0x0a, 0x0a,
	0xff, 0xb1, 0x0d, 0x71, 0x94, 0xf1, 0xc1, 0xa5, 0xcf, 0x73, 0x22, 0xec,
	0x1a, 0xe0, 0x96, 0x4e, 0xd4, 0xbf, 0x12, 0x27, 0x46, 0xe0, 0x87, 0xfd,
	0xb5, 0xb3, 0xe9, 0x1b, 0x34, 0x93, 0xd5, 0xbb, 0x98, 0xfa, 0xed, 0x49,
	0xe8, 0x5f, 0x13, 0x0f, 0xc8, 0xa4, 0x59, 0xb7
};

/* "Entropy" from buffer */
static size_t test_offset;
static int hmac_drbg_self_test_entropy(void *data, unsigned char *buf, size_t len)
{
	const unsigned char *p = data;
	memcpy(buf, p + test_offset, len);
	test_offset += len;
	return (0);
}

#define CHK(c)    if ((c) != 0)                          \
		{                                       \
			if (verbose != 0)                  \
			mbedtls_printf("failed\n");  \
			return(1);                        \
		}

/*
 * Checkup routine for HMAC_DRBG with SHA-1
 */
int mbedtls_hmac_drbg_self_test(int verbose)
{
	mbedtls_hmac_drbg_context ctx;
	unsigned char buf[OUTPUT_LEN];
	const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type(MBEDTLS_MD_SHA1);

	mbedtls_hmac_drbg_init(&ctx);

	/*
	 * PR = True
	 */
	if (verbose != 0) {
		mbedtls_printf("  HMAC_DRBG (PR = True) : ");
	}

	test_offset = 0;
	CHK(mbedtls_hmac_drbg_seed(&ctx, md_info, hmac_drbg_self_test_entropy, (void *)entropy_pr, NULL, 0));
	mbedtls_hmac_drbg_set_prediction_resistance(&ctx, MBEDTLS_HMAC_DRBG_PR_ON);
	CHK(mbedtls_hmac_drbg_random(&ctx, buf, OUTPUT_LEN));
	CHK(mbedtls_hmac_drbg_random(&ctx, buf, OUTPUT_LEN));
	CHK(memcmp(buf, result_pr, OUTPUT_LEN));
	mbedtls_hmac_drbg_free(&ctx);

	mbedtls_hmac_drbg_free(&ctx);

	if (verbose != 0) {
		mbedtls_printf("passed\n");
	}

	/*
	 * PR = False
	 */
	if (verbose != 0) {
		mbedtls_printf("  HMAC_DRBG (PR = False) : ");
	}

	mbedtls_hmac_drbg_init(&ctx);

	test_offset = 0;
	CHK(mbedtls_hmac_drbg_seed(&ctx, md_info, hmac_drbg_self_test_entropy, (void *)entropy_nopr, NULL, 0));
	CHK(mbedtls_hmac_drbg_reseed(&ctx, NULL, 0));
	CHK(mbedtls_hmac_drbg_random(&ctx, buf, OUTPUT_LEN));
	CHK(mbedtls_hmac_drbg_random(&ctx, buf, OUTPUT_LEN));
	CHK(memcmp(buf, result_nopr, OUTPUT_LEN));
	mbedtls_hmac_drbg_free(&ctx);

	mbedtls_hmac_drbg_free(&ctx);

	if (verbose != 0) {
		mbedtls_printf("passed\n");
	}

	if (verbose != 0) {
		mbedtls_printf("\n");
	}

	return (0);
}
#endif							/* MBEDTLS_SHA1_C */
#endif							/* MBEDTLS_SELF_TEST */

#endif							/* MBEDTLS_HMAC_DRBG_C */
